Commitments and Contingencies (Details Textual) (USD $)	3 Months Ended			3 Months Ended			3 Months Ended
	Sep. 30, 2013 sites	Dec. 31, 2012	Aug. 18, 2011 Sem Crude [Member] bbl	Sep. 30, 2013 Crude [Member] sites	Sep. 30, 2013 SemGas [Member] sites	Sep. 30, 2013 SemCAMS [Member]	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]	Sep. 30, 2013 Capacity [Member] SemGas [Member]	Sep. 30, 2013 Commitments [Member] SemGas [Member]
Commitments and Contingencies (Textual) [Abstract]
Loss contingency claims, number of barrels of crude oil claimed to be owed			141,000
Site contingency number of sites checked	6			5	1
Number of sites requiring remediation and water contamination as per phase two investigations	4
Accrued liability, estimated fines and environmental contributions						$ 400,000
Asset retirement obligation liability						42,100,000
Estimated cost to retire facilities						104,600,000
Notice required to cancel purchase agreements, days							30 days	120 days
Due under the contract	81,509,000	63,831,000								25,800
Future obligations									$ 88,200,000